1. Field of the Invention
The present invention relates generally to the cooling of electronic systems having multiple heat dissipating components such as processors and, more particularly, to managing heat sink fan(s) based on performance requirements.
2. Related Art
CPUs, CECs (generally, processors) and other heat dissipating components found in typical computer servers generally include a heat sink attached to a given component. These heat sinks often include a fan that pushes air through the heat sink and/or the component in order to keep the heat dissipating component from overheating. As electronic systems become more densely packaged and designing electronic systems within power and heat dissipation budgets becomes more difficult, a number of design challenges arise with respect to the power used by the fans and the effect of the fans on the heat dissipation characteristics of the overall system.
As an example of such densely packaged electronic systems, advances in the miniaturization of computer, communication and other electronic equipment have led to the development of so-called “blade” systems, which permit several circuit boards (“blades”) to be installed in a single chassis. The chassis typically includes components, such as power supplies, cooling fans, a blade manager, and other components that are shared by all the blades installed in the chassis. The blades typically plug into a backplane of the chassis, which distributes power and data signals between the blades, blade manager, and other components. This arrangement enables a large number of blades to be housed in a relatively small chassis. Oftentimes, the chassis is dimensioned to be mounted in a rack, such as a server rack with other rack-mounted equipment.
Blades can perform various functions. Most blades contain entire computers, including single or multiple processors, memory, and network interfaces. Most computer blades are used as servers while others are used as communication devices, such as routers, firewalls or switches. Some blades contain specialized hardware components, in addition to or instead of processors, memory, etc. In general, blades include any number of heat dissipating components.
Some server blades include disk drives. Other blades access disk drives that are located elsewhere in the chassis or are connected to the chassis by computer network hardware. Typically, any type of blade can be plugged into any slot of a chassis. This enables an operator or system manager to “mix and match” blades in a chassis so that requisite operations can be performed by the blade system. In addition, the mixture of blade types can be changed to accommodate changes in operational requirements. For example, a system operator might choose to logically connect a blade to different disk drives to execute different application programs at different times of a day. In another example, if a blade fails, logical connections from off-blade disk drives that were formerly used by the failed blade can be redirected to a replacement or hot standby blade.
As noted above, while such densely packaged electronic systems as blade systems provide many advantages, several engineering challenges arise when using them. Among these challenges is the challenge of designing and operating a bladed system such that sufficient heat is dissipated in the limited space available in the chassis that hosts the system. Some known power limiting strategies include powering down a CPU functional unit, e.g., a floating point unit or an on-die cache, or trading off speed for reduced power consumption in a hard drive. To address heat dissipation challenges, bladed server systems can be designed with an underlying power and thermal envelope. For example, when a chassis that hosts a bladed system has a limited amount of airflow available to cool the blades (i.e., when the system can only dissipate a limited amount of heat), then the chassis is designed for a limited amount of power consumption and an associated limited performance of the blades.
As a result of the modularity, flexibility, and requirements of such bladed systems however, different portions of the system, including different blades and even different heat dissipating components, will have varied heat dissipation needs that will further vary over time given changes in operating conditions of the components and blades. In typical systems, the fans associated with heat dissipating components simply run at full speed at all times. In other systems, the speed of all fans can be varied together based on an overall system temperature.